Magnetic resonance imaging in the assessment of cervical nodal metastasis in oral squamous cell carcinoma

Computed tomography versus magnetic resonance imaging for diagnosing cervical lymph node metastasis of head and neck cancer: a systematic review and meta-analysis

Computed tomography (CT) and magnetic resonance imaging (MRI) are common imaging methods to detect cervical lymph node metastasis of head and neck cancer. We aimed to assess the diagnostic efficacy of CT and MRI in detecting cervical lymph node metastasis, and to establish unified diagnostic criteria via systematic review and meta-analysis. A systematic literature search in five databases until January 2014 was carried out. All retrieved studies were reviewed and eligible studies were qualitatively summarized. Besides pooling the sensitivity (SEN) and specificity (SPE) data of CT and MRI, summary receiver operating characteristic curves were generated. A total of 63 studies including 3,029 participants were involved. The pooled results of meta-analysis showed that CT had a higher SEN (0.77 [95% confidence interval {CI} 0.73–0.87]) than MRI (0.72 [95% CI 0.70–0.74]) when node was considered as unit of analysis (P<0.05); MRI had a higher SPE (0.81 [95% CI 0.80–0.82]) than CT (0.72 [95% CI 0.69–0.74]) when neck level was considered as unit of analysis (P<0.05) and MRI had a higher area under concentration-time curve than CT when the patient was considered as unit of analysis (P<0.05). With regards to diagnostic criteria, for MRI, the results showed that the minimal axial diameter of 10 mm could be considered as the best size criterion, compared to 12 mm for CT. Overall, MRI conferred significantly higher SPE while CT demonstrated higher SEN. The diagnostic criteria for MRI and CT on size of metastatic lymph nodes were suggested as 10 and 12 mm, respectively.

Improving target definition for head and neck radiotherapy: a place for magnetic resonance imaging and 18-fluoride fluorodeoxyglucose positron emission tomography?

Defining the target for head and neck radiotherapy is a critical issue with the introduction of steep dose gradients associated with intensity-modulated radiotherapy. Tumour delineation inaccuracies are a major source of error in radiotherapy planning. The integration of 18-fluoride fluorodeoxyglucose positron emission tomography ((18)FDG-PET) and magnetic resonance imaging directly into the radiotherapy planning process has the potential to greatly improve target identification/selection and delineation. This raises a range of new issues surrounding image co-registration, delineation methodology and the use of functional data and treatment adaptation. This overview will discuss the practical aspects of integrating (18)FDG-PET and magnetic resonance imaging into head and neck radiotherapy planning.

The Impact of (18)F-FDG PET CT Prior to Chemoradiotherapy for Stage III/IV Head and Neck Squamous Cell Carcinoma

Introduction. To determine the value of a FDG-PET-CT scan in patients with locally advanced head and neck squamous cell carcinoma (HNSCC) prior to chemoradiotherapy. Materials and Methods. Consecutive patients with stage III or IV HNSCC who had undergone a staging FDG-PET-CT scan prior to chemoradiotherapy between August 2008 and April 2011 were included. Clinical details and conventional imaging (CT and/or MRI) were, retrospectively, reviewed, a TNM stage was assigned, and levels of cervical lymph node involvement were documented. This process was repeated with the addition of FDG-PET-CT. Radiotherapy plans were reviewed for patients with an alteration identified on TNM staging and/or nodal level identification with FDG-PET-CT and potential alterations in radiotherapy planning were documented. Results. 55 patients were included in the analysis. FDG-PET-CT altered the TNM stage in 17/55 (31%) of patients, upstaging disease in 11 (20%) and downstaging in 6 (11%); distant metastases were identified by FDG-PET-CT in 1 (2%) patient. FDG-PET-CT altered the lymph node levels identified in 22 patients (40%), upclassifying disease in 16 (29%) and downclassifying in 6 (11%). Radiotherapy plans were judged retrospectively to have been altered by FDG-PET-CT in 10 patients (18%). Conclusions. The use of FDG-PET-CT potentially impacts upon both treatment decisions and radiotherapy planning.

Accuracy of MRI in prediction of tumour thickness and nodal stage in oral squamous cell carcinoma

We aim to compare radiological with histological tumour thickness (RTT with HTT) for oral squamous cell carcinoma (OSCC), and the ability of both to predict cervical metastasis. The MRI images and histopathology reports of 102 consecutive OSCC cases were compared and the relationship between RTT and HTT, calculated as a "shrinkage factor" by the gradient of the best fitting regression line. Most (69%) tumours appeared thicker on MRI than was revealed by histopathology. Shrinkage factor was 0.70 (interquartile range 0.63-0.77, correlation co-efficient 0.63) for all cases, 0.87 (IQR 0.80-0.95, CC 0.88) for tongue and 0.65 (IQR 0.49-0.82, CC 0.45) for floor of mouth sub-sites. RTT did not correlate well with the presence of nodal metastases in any sub-site, i.e. there was no clinically applicable cut-off value of RTT to determine the prescription of elective neck dissection. Although RTT has some predictable relationship with HTT, this varies between sub-sites with tongue the most accurately predicted shrinkage using axial MRI. It is not possible from either the MRI staging of neck or tumour thickness to safely determine the need for neck dissection in OSCC. It is necessary to re-evaluate the benefit of MRI as a staging investigation (particularly for early stage OSCC) and further explore the contribution of molecular biomarkers and ultrasound.

Detection of lymph node metastases by gadolinium-enhanced magnetic resonance imaging: systematic review and meta-analysis

BACKGROUND

Gadolinium-based contrast agents are used with magnetic resonance imaging (MRI) to highlight tumor vascularity in organs. They are also widely used for primary tumor visualization. We conducted a systematic review and meta-analysis of the existing evidence of the accuracy of gadolinium-enhanced MRI for staging lymph node metastases.

METHODS

We systematically searched the MEDLINE, Cochrane, CANCERLIT, and EMBASE databases for studies published in English or German from January 1, 1988, to January 1, 2008, that assessed the diagnostic accuracy of gadolinium-enhanced MRI in the evaluation of lymphatic metastases compared with histopathologic examination as the reference test. Based on a priori-defined clinical considerations, we studied three subgroups of studies: those that used a single malignancy criterion and those that used multiple malignancy criteria with or without contrast highlighting. Summaries of MRI sensitivity and specificity for detecting lymph node metastases were calculated using a bivariate regression model. All statistical tests were two-sided.

RESULTS

The literature search yielded 43 full-text papers that were considered for inclusion in the meta-analysis. We performed quantitative pooled analyses on the 32 studies that provided data on patient-level diagnosis. The weighted estimates of sensitivity and specificity for all studies combined were 0.72 (95% confidence interval [CI] = 0.66 to 0.79) and 0.87 (95% CI = 0.82 to 0.91). Estimates of sensitivity and specificity were essentially unchanged for studies that used a single malignancy criterion (0.71 [95% CI = 0.61 to 0.79] and 0.88 [95% CI = 0.80 to 0.93], respectively; n = 11 studies) or multiple malignancy criteria without contrast enhancement (0.70 [95% CI = 0.58 to 0.79] and 0.86 [95% CI = 0.68 to 0.94], respectively; n = 6 studies). The sensitivity increased to 0.84 (95% CI = 0.70 to 0.92), with a specificity of 0.82 (95% CI = 0.72 to 0.89) for the nine studies that incorporated contrast enhancement in their multiple malignancy criteria. Six studies did not define the malignancy criteria they used.

CONCLUSIONS

The overall accuracy of gadolinium-enhanced magnetic resonance imaging for the detection of nodal metastases is moderate. Incorporating contrast enhancement in the malignancy criteria substantially improves the accuracy of this diagnostic test.

Can FDG-PET assist in radiotherapy target volume definition of metastatic lymph nodes in head-and-neck cancer?

BACKGROUND AND PURPOSE

The role of FDG-PET in radiotherapy target volume definition of the neck was evaluated by comparing eight methods of FDG-PET segmentation to the current CT-based practice of lymph node assessment in head-and-neck cancer patients.

MATERIALS AND METHODS

Seventy-eight head-and-neck cancer patients underwent coregistered CT- and FDG-PET scans. Lymph nodes were classified as "enlarged" if the shortest axial diameter on CT was 10mm, and as "marginally enlarged" if it was 7-10mm. Subsequently, lymph nodes were assessed on FDG-PET applying eight segmentation methods: visual interpretation (PET(VIS)), applying fixed thresholds at a standardized uptake value (SUV) of 2.5 and at 40% and 50% of the maximum signal intensity of the primary tumor (PET(SUV), PET(40%), PET(50%)) and applying a variable threshold based on the signal-to-background ratio (PET(SBR)). Finally, PET(40%N), PET(50%N) and PET(SBRN) were acquired using the signal of the lymph node as the threshold reference.

RESULTS

Of 108 nodes classified as "enlarged" on CT, 75% were also identified by PET(VIS), 59% by PET(40%), 43% by PET(50%) and 43% by PET(SBR). Of 100 nodes classified as "marginally enlarged", only a minority were visualized by FDG-PET. The respective numbers were 26%, 10%, 7% and 8% for PET(VIS), PET(40%), PET(50%) and PET(SBR). PET(40%N), PET(50%N) and PET(SBRN), respectively, identified 66%, 82% and 96% of the PET(VIS)-positive nodes.

CONCLUSIONS

Many lymph nodes that are enlarged and considered metastatic by standard CT-based criteria appear to be negative on FDG-PET scan. Alternately, a small proportion of marginally enlarged nodes are positive on FDG-PET scan. However, the results are largely dependent on the PET segmentation tool used, and until proper validation FDG-PET is not recommended for target volume definition of metastatic lymph nodes in routine practice.

Detection of cervical intranodal metastasis in oral cancer using elastic scattering spectroscopy

While histopathology remains the gold standard for tissue diagnosis, several new diagnostic techniques are being developed that rely on physical and biochemical changes that mirror or precede malignant change within tissue. The aim of this study was to compare findings of elastic scattering spectroscopy (ESS) with histopathology on formalin fixed neck dissection specimens to see if this technique could be used as an adjunct or alternative to histopathology in defining nodal involvement. The technique involves the use of Mie scattering and is a simple non-invasive method of tissue interrogation. One hundred and thirty lymph nodes were examined from 13 patients who underwent neck dissection. The nodes were formalin fixed, bivalved and examined by ESS using a pulsed xenon lamp. The intensity of the spectrum at 4 points was considered for comparison; at 360, 450, 630 and 690 nm. The nodes were then routinely processed and haematoxylin and eosin-stained sections examined histopathologically, and the results compared. Using this technique, a sensitivity of 98% and a specificity of 68% were obtained.

MR imaging of lymph nodes in the head and neck

This article reviews imaging-based nodal classification, recent advancements in MR imaging techniques for lymph node imaging, and characteristics of MR imaging for necklymphadenopathy. Further technical development of MR imaging is necessary to improve accuracy of diagnosis of lymph node metastases in patients with no head and neck cancer. Development of new tissue-specific MR contrast agents and functional imaging studies to address biologic activity of lymph nodes is essential in the future.

MR imaging of lymph nodes in the head and neck

This article reviews imaging-based nodal classification, recent advancements in MR techniques for lymph node imaging, and characteristics of MR imaging for neck lymphadenopathy. Further technical development of MR imaging is necessary to improve accuracy of lymph node metastases in patients with N0 neck. Development of new tissue-specific MR contrast agents and functional imaging studies to address biologic activity of lymph nodes are essential in the future.

Error in radiology

Literature review indicates high levels of error within radiology. The aetiology of radiological error is multi-factorial. While individuals have a duty to progressively improve their performance, the experience of safety cultures in other high-risk human activities has shown that a system approach of root cause analysis is the method required to reduce error significantly.

How accurate is cancer scan reporting?

The wide recognition of advances in medical imaging need to be matched by an awareness of the significant error rates in radiological interpretation of cancer scans. Common errors, their aetiology and potential solutions are discussed. Internet awareness of these errors has appeared.